Hollow Wooden Surfboard - My Magic Carpet

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Introduction: Hollow Wooden Surfboard - My Magic Carpet

Welcome to my first instructable. I've made a few wooden surfboards so thought I would share my favourite. It's 7'6 x 21" x 2"3/4 magic carpet design, a mellow cruiser good for lazy days and lazy waves.


Plans link:

https://www.dropbox.com/s/30ky3c3vte4nw5q/7%276%20...

Step 1: Glue the Pattern to the Plywood

So, there are places online where you can buy the plans, or you can design your own. I use a program called AKU. Using this you can create designs pretty quickly. For wooden boards you need to create slices every 150mm that define your ribs. The central spine is the side profile. The outline is your final planshape. Think of it as a fishbone with a spine and ribs that you then build the decks and rails around.
I then use a program called hollow board template maker that generates a PDF of the spine, ribs and outline. Print out at full size and using spray mount stick onto 4mm plywood.

The whole build thread is here: also, with lots of cool surfboard projects
http://www.grainsurf.com/forum/viewtopic.php?f=11&t=5532


Step 2: Cut the Frame

I use a bandsaw to cut out all the frame parts, then dry fit it together. As the design fits onto a 1200x2400mm sheet you can get the frame and the whole bottom deck out of one piece of ply. Sit the frame onto the bottom deck and draw on the rib and spine positions. This is your guide for where a bead of PU glue will go. For this build I used little blocks of balsa wood that keep the frame straight and the ribs 90deg to the spine.

Step 3: Glue the Frame to the Plywood

I made a clamping frame using 3x2 timber, threaded bar and some nuts and penny washers. You'll see how it works but the idea is the board is clamped every 200mm between two strips of ply that can be adjusted to fit the top and bottom rocker of the board using the threaded bar and some nuts.
Bead the PU glue onto the bottom deck, fit the frame and clamp in place.

Time taken so far about three hours - relax till tomorrow while the PU glue cures.

Next add the chine strip - 6x6mm stripwood. This glues into place into notches cut on the rib ends and gives you the outline shape. I'll add the rail strips next, but first some hardware considerations.

Step 4: Fin Box Support

At the tail of the board I add some scrap foam floor insulation blocks. These form support for the finbox and the leash plug when they get holes routered in place and glued in later on. There is also a vent to fit to the frame - for this I use a brass insert pressed into a wooden block then glued to the spine to fit flush with the underside of the deck. As the board is hollow, the air inside can expand and burst the board on a hot day. Using a vent means you can equalise the pressure so the board doesn't suck air in or blow! The vent will be sealed up with a brass bolt and rubber washer.

Step 5: Cut and Glue the Deck

Next I cut the strips for the top deck. These need to be 6mm thick and ideally longer than the board so no scarfing needed. I used some reclaimed western red cedar and pine. The nail stains will look good. The strips can be edge glued using titebond 3 and masking tape. I glue up in twos and threes - no need to do the whole deck in one piece.

Step 6: Rail Strips

Cut some 6x6mm and 6x12mm strips - these get glued to the ends of the ribs to form the rails using any clamping method you can use. Like the drainpipe clamps? Cut an inch off a drainpipe, cut a slot and you have a clamp. I have a box of about 40. You need a lot of clamps for rails. Glue up one strip at a time, using a plane to bevel the strips and taper at the ends. PU glue helps full any gaps you have.

Step 7: Top Deck

Now we add the deck, a strip or two at a time. You need to trim each deck panel to fit against the rails using bandsaw and plane. Glue using PU and don't forget about the vent!

Step 8: Ready for Final Shaping

Once you have it all glued up and cured its ready for shaping. The deck strips take about four or five days to shape and glue. Reckon on an hour or so per panel plus overnight cure time. Now comes a lot of sanding - I use a belt sander and take care to work evenly around the board. Step back and eyeball regularly to keep it symmetrical. Measure, look and measure. This is also the time when you realise the board rattles and you can't find you pencil.

Step 9: Seal the Top

Here's where it gets a little crazy. I seal the top deck using resin research epoxy having masked out the rails. I'm going to do a Mexican blanket resin job on the bottom (crappy ply) and leave the wood exposed on top. This is where the colour of the grain POPs and you see what you have. The positive negative stripes have come out well.

Step 10: Glassing

I have my design worked out and taped to the wall. I add a layer of 4oz fibre glass weave to the bottom and tape in place. The top is masked out. Next I mix up the pigments and resin batches. I'm using polyester resin so add 5ml pigment into 100ml resin and mix well. Do not add catalyst yet! Put gloves, respirator and goggles on, get your squeegee ready and catalyse the first colour. Pour across on bands, then choose the next colour and repeat.

Step 11:

Step 12: Glass the Top

Trim the rail laps with a very sharp blade when the resin loses its tack but is not fully cured. Leave overnight to cure then glass the top. I've added my pinlines (vinyl car stripes from eBay and they are self adhesive) and logo laser printed onto rice paper and laid under the glass. Leave to cure then gloss coat both sides. Polyester resin again but adding wax in styrene so it cures smooth and non tacky. You'll see I already fitted the leash plug and sealed up level with plasticine before glassing - you can open these up afterwards with a Dremel.

Step 13: Pinline and Finbox

Add the pinline before the gloss then router out the finbox slot. The finbox gets glued in with a paste if fibreglass and resin. For the leash plug use a forstner bit and glue in the same way.

Now just the sanded finish to do - wet and dry paper from #400 right up to #1500 and we're done.

Step 14: Done

Step 15: Here's Some Others

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88 Discussions

Hi - the grain surf link doesn’t seem to work, is there another link to the full build? Cheers Jon

1 more answer

Hi, Can you explain more about how to create this stripes?
"reclaimed western red cedar and pine"
Did you cut them yourself? How?

1 more answer

Hi - the deck planks were cut using a tablesaw - 6mm thick and differing widths (the maximum width I could cut was 75mmx6mm). You could get a timber yard to do this for you, or even find (like I did) the western red cedar at 6mm thicknesses. These were then edge glued together in the arrangement I wanted. To do this, lay the boards flat and masking tape the joins together. Then, flip the set over and by "hinging" open each join you can run a bead of glue down the edges. Then, lay flat, weigh down (or sash clamp) the panel together and leave overnight to dry. Hope this help[s!

Hi there, I'm building a hollow Tom Blake design paddle board. Am having problems finding a brass or stainless steel air vent. Can only find plastic but not interested. Could you advise a place of purchase for a decent, original looking vent. Many thanks, Dave.



1 more answer

Where are you? I got my brass ones as free samples from Anchor Inserts in the UK. Any supplier to the injection moulding industry should be able to help, or you could make your own out of a pice of brass - drill right through then tap an M6 thread

I just used 3mm exterior ply - it is cheap and gets wrapped in fibreglass so doesn’t really matter.

Do you have plans for a version with solid rails? Seen it mentioned on a forum.

Hi, I'm currently in the process of making this board. I'm wondering if I could get a more in-depth explanation on where/how to place the vent?

Also, when routing the finbox, should I router into the spine of the board's skeleton, or slightly off center? I was thinking of installing just a single fin.

1 reply

Finbox - this must be central so
you must cut into the stringer. However, as you will have put support blocks
either side then this means you have plenty of material to glue the finbox
into. I put it 140mm from the tail of the board so the finbox would be in
contact with the underside of the top deck at the tail. It should be a tight
fit. Roughen the glue surfaces of the finbox then mix up a thin paste of epoxy
plus wood flour (from a sander - peanut butter consistency when mixed), spread
inside the hole and on the finbox and push into place. You may need to hold it
with a couple of clamps rather end of a strip of wood running across the board.
Place a fin in the box and check it sits vertical... you can see I made a
simple router jig and used the collar on my router plus the cutter size to work
out the dimensions of this. Go careful with the cut depth and measure carefully
- the last thing you want to do is burst through the top deck of the board.
Measure the finbox depth and check in relation to the board. The plastic tabs on the finbox help set the depth, then you sand all this down after glassing (or even before - I usually sand the finbox first then glass over the top to ensure a good seal but if I ever knock a fin and rip out the finbox then it means a full re-glass. Remember to tape over the fin slot if you do this method).

Vent is a little easier -
make up a block (I use something like 15mm ply and about 50x50mm). Drill and
fit the vent into this. The vents I use are brass threaded inserts and are
square so drill a hole then chisel square. Use a bit of epoxy peanut butter to
bond it in to the block. Then glue the block to the stringer and a rib at the
nose of the board. anywhere in the first foot of length of the board so up against the second rib is a good place. This means the vent is off centre. Measure where the vent is
when gluing on the deck planks (you can see my marking lines on the plank over the vent), transfer the position to the deck plank then drill a small pilot hole so that the board is vented. Prior to glassing I fill this hole up with plasticene or blue-tak and glass over the top. Then after glassing drill a hole say 12mm in the plank so that when this plank is glued in
place it sits directly over the vent. Make user all ribs and stringer have been
drilled so all compartments can breathe. You could fit the vent into the
stringer if you want it central - you just cut a pocket for the vent to sit in
but you will have to support either side. This pocket has to be deeper than the
vent so that it can breath. Remember though at the nose the stringer is pretty shallow so can easily snap...To seal it use a stainless or brass bolt with
a rubber o ring. Make sure your surf bag or fin bag has an Allen key that fits
the vent or you could use a hex-bolt and cut a slot in the head so it can be coin operated.... I have burst a board in the UK when forgetting to open up the vent
on a warm day so never skip the vent...

0
user
M4RM

1 year ago

To make sure I taped the printout together correctly, What are the nose and tail rocker dim's?

4 replies

should be 7'6" nose to tail overall length on the plans

thanks, I have the 7'6", what i'm concerned about the rocker dimentions. The nose rocker only looks to be about 2.5", is this correct? as a longboard is typically in the 3.5"-5" range. and the tail rocker is about the same as the nose..

Those dimensions sound right too - the design is pretty flat rockerwise, slightly less on the tail.

looking forward to see some pics!

at this point I plan on mixing it up a bit. so I won't have to put in a pressure valve, I am planning to shape a xps 1# blank with a wood stringer & "shell". expanding the plans from 7'6" to 8' for more volume for my larger size. perhaps a few yards of a nice cotton material with a print in the epoxy. i hope the low weight xps should not matter with a tough wood/epoxy shell. lets see what happens....

Wooden blocks fine for the fins. Check the pictures for how I do my vent - I make sure the vent block is glued to the sound and a rib.

Wet sanding by hand keeps the dust down. Also, regarding clamps- I've seen people use bike inner tubes, bungees and straps. The main thing is that you squeeze the rail strips together and to the rib. Good luck!

Just giving a progress update, Im working with what I have, I dont have a clamping rig or that much time to build one nor do I have access to 40+ clamps, so I am improvising. My next question is how do I make support for the fins? I dont know how to get my hands on blocks of foam, I have some wood I can use and just glue it to the bottom of the board and then router in a slot for the fins when I finish the rails and the top. Any suggestions on fin/vent support in the board so that I dont accidently hit the fins the wrong way and it cracks the fiberglass because there is no support for them?

Also you mentioned when the glass hardens, sanding it becomes an issue for breathing without a respirator, is it still bad for your health if you sand it by hand like without a power sander, but instead with a sanding block?

Thanks again for these responses, Im very excited to eventually use this board!!

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Thanks for the response!

This is my progress so far, I have yet to glue the skeleton together but so far its not looking too bad. My next question is about the fiberglass/resin application. I have never worked with those materials so im not sure how to do it properly, do you know of any tips/youtube tutorials that could show me the correct way to do it? Also Im worried about the vapors, I will probably be working in the garage which has poor insulation so Im concerned about the toxic fumes seeping into the house in the rooms close to the garage. Is there something I should do to prevent this? Or should I do the application outside?

Thanks again for the response, and also I think some other comments were asking about how to print the plans full size? The way I did this was to open the downloaded PDF in Adobe Reader, and then go Print>Poster and then print it under that tab. There are other ways to do this, its called 'Tiled Printing' apparently.

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